Since the first mechanical propulsion systems were adapted to maritime use, mariners as well as maritime engineers have been concerned with providing the most powerful and yet compact system possible for not only aiding in the maneuvering of relatively large vessels in restricted areas and during special maneuvering such as docking, but also have been used in the marine construction field for maneuvering barges, cranes, dredges and the like during the performance of various construction functions.
The various vessels used in performing these marine tasks have included large propellers driven at a relatively low speed by powerful engines. The more powerful the tug, the larger the engine and thus the larger the boat to house the same. On many occasions, particularly in the marine construction industry, large powerful tugs are required and yet, due to draft limitations, they cannot be practically employed. Further large powerful, shallow draft tugs have not been believed to be practical from either a technical or economic viewpoint.
After much research and study into the above-mentioned problems, the present invention has been developed to provide a powerful, shallow draft tug vessel of relatively short length that is particularly adapted for use on inland waters where varying depths are routinely encountered. This improved tug means further has the capability of allowing additional propulsion units to be added to increase the power of the system without increasing its length, draft or ability to maneuver.
The above is accomplished through the use of individual hull type floats or pontoons which are interconnected with the propulsion system pivotably mounted therebetween so that the depth of the propeller, rudders, etc., can be raised and lowered as necessary. Additional floats and propulsion units can be added without increasing the draft of the integrated tug system. Further, hauling for maintenance and/or repairs can be accomplished without removal of the tug from the water and in fact worn or damaged propulsion units can be removed and replaced in their entirety thereby giving the system of the present invention even greater versatility.
In view of the above, it is an object that the present invention to provide a powerful yet compact marine vessel.
Another object of the present invention is to provide a powerful, compact and yet shallow draft marine vessel particularly adapted to tug operations.
Another object of the present invention is to provide a powerful, shallow draft, compact tug type marine vessel wherein the operating depth thereof can be readily varied.
Another object of the present invention is to provide a tug type vessel which can operate in both deep and shallow waters.
Another object of the present invention is to provide a tug type vessel which includes a pivotable propulsion system.
Another object of the present invention is to provide, in a tug type vessel, a propulsion system wherein the underwater portion is readily removable from the water for maintenance and/or repair without dry docking of the vessel.
Another object of the present invention is to provide a tug type vessel wherein additional propulsion systems can be readily added or removed as the situation dictates.
Another object of the present invention is to provide a powerful tug type vessel which is short in length and shallow in draft.
Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention.